Erasable ink is characterized in that when letters, characters, figures or drawings are written or drawn on paper in such ink, the lines drawn can be erased with a rubber eraser. It is currently used in felt-tip pens and the like.
Such erasable inks are already known. There is known, for instance, an erasable ink composition characterized in that it comprises a resin having a film-forming temperature not higher than 0.degree. C. or a glass transition temperature not higher than 0.degree. C., spherical particles of a colored resin having a particle size of 1 to 20 .mu.m and water and has an ink viscosity of 5 to 35 mPa.cndot.sec (Japanese Kokai Tokkyo Koho H05-279614).
In the case of said erasable ink composition, however, it is difficult to erase drawn lines completely and, from the erasability viewpoint, there is room for improvement. In particular, when writing is made with a great tool force, it is impossible to erase the drawn lines to the extent that they cannot be recognized any longer. This problem becomes more serious when such composition is used as ink for ballpoint pens with which the tool force tends to become high. Furthermore, when the ink composition mentioned above is to be used as ink for ballpoint pens, it tends to fail to flow out successfully, hence, as it is, such composition cannot be used in ballpoint pens.